Deck 12: Concrete Masonry

Question 1

What is the coefficient of thermal expansion and how is it used with regard to concrete masonry?

Answer 1

The coefficient of thermal expansion is used to calculate the amount of expansion that can be expected as temperatures change. Concrete masonry units expand when heated and contract when cooled. These changes are reversible, and the unit returns to its original size after the temperature returns to the point at which the change started. Since the aggregate makes up about 80 percent of a unit, the coefficient of expansion of the aggregate is a major factor influencing expansion and contraction of the concrete masonry unit.

Question 2

What is a slump block?

Answer 2

Slump block is a concrete masonry block that is removed from the mold before it has had a chance to set completely. This causes the concrete block to retain a slightly slumped appearance. The units have irregular faces and some differences in height and surface texture, giving a rustic appearance when laid into a wall.

Question 3

Describe the properties of faced blocks.

Answer 3

Faced blocks have the exposed surface covered with a ceramic glaze or a plastic overlay, or they are polished by grinding the surface smooth. Decorative blocks, such as fluted or scored, are made with many different face designs. Typically they are pierced or recessed to produce an unusual patterned wall surface. A decorative privacy wall is an example. Common sizes are 8 X 16 in. and 12 X 12 in. Special designs can be made by the block manufacturer to meet the requirements of an architect.

Question 4

Two ____ of concrete masonry units are specified by ASTM C90: Type I and Type II.

A) types
B) weights
C) grades
D) standards

Question 5

Describe the manufacturing process for concrete masonry units from the use of an autoclave until completion.

Question 6

____ are made either solid or with a depressed area called a frog.

A) Concrete blocks
B) Slump blocks
C) Concrete bricks
D) Modular bricks

Question 7

____ are available in sizes ranging from rectangular units for small residential walls to large, multi-piece units suitable for high walls and large retaining walls, like those used for highway construction.

A) Autoclaved aerated concrete blocks
B) Split-face blocks
C) Lintel blocks
D) Precast concrete retaining wall units

Question 8

The coefficient of ____ is used to calculate the amount of expansion that can be expected as temperatures change.

A) insulation
B) thermal expansion
C) heat transmission
D) fire resistance

Question 9

____ data give a means of determining a unit's ability to carry loads and withstand structural stresses.

A) Compressive strength
B) Weight
C) Absorption
D) Thermal expansion

Question 10

Describe the characteristics of concrete block cores.